The Java code gets turned into a Wasm binary, which exposes hooks you call from JavaScript. Wasm is available on all the major modern browsers, so you can use it now.

When the binary stream is very large, the overhead of adding 448 bytes (the code above in the sequence corresponding to byte values 0, 1, … 255) to define the mapping is negligible. My team ...

Now, with what the company calls the XobotOS Research Project, the Java layer has been removed via a "machine translation of Android from Java to C#," according to a blog post from Xamarin CTO Miguel ...